The six schools are:
M.S. Carriers Professional Driving Academy, Phoenix, AZ; CDL Plus, Fort Wayne, IN; ProDrive of Maine, Portland; Southern Missouri Truck Driving School, Malden; Rogue Community College, White City, OR; and Tennessee Technology Center, Nashville.
PTDI certification was revised last year to improve skill standards, curriculum guidelines and certification procedures. The certification process incorporates the Federal Highway Administration's "Minimum Standards for Training Tractor-Trailer Drivers," and includes an onsite evalutaion team, which examines the school's existing standards, procedures and practices.